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Preparation method of mercaptoacetic acid-2-ethylhexyl in molten salt hydrate

A technology of thioglycolic acid and ethylhexyl, which is applied in the field of preparation of thioglycolic acid-2-ethylhexyl, can solve the problem of restricting the output of thioglycolic acid-2-ethylhexyl, large amount of extractant, complicated technological process, etc. problems, to achieve the effect of simplifying the production process, simplifying separation, and reducing side reactions

Active Publication Date: 2022-07-29
山东沾化金嘉利化工科技有限公司
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AI Technical Summary

Problems solved by technology

[0004] In the aqueous solution of thioglycolic acid produced by the sodium hydrosulfide method, the content of thioglycolic acid is usually 10-15%. In order to reduce the introduction of other components, when carrying out the synthesis of thioglycolic acid-2-ethylhexyl, it is usually based on 2- Ethylhexanol is used as the extraction agent, and the production process of four extractions and three esterifications is adopted. The process is complicated, the energy consumption is high, the amount of extraction agent is large, the loss is high, and the extraction is not thorough enough. The raffinate after extraction contains about 20 % NaCl, COD is usually 15000-20000mg / L, which brings certain difficulties to subsequent wastewater treatment
Therefore, greatly restricting the promotion of thioglycolate-2-ethylhexyl output, the production cost of product is high
Because 2-ethylhexyl thioglycolate contains -SH bonds, it is prone to oxidation reaction to generate dithiodiacetate esters in the production process, resulting in low yield, which is also a restriction for domestic thioglycolic acid and its ester manufacturers. technical bottleneck

Method used

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  • Preparation method of mercaptoacetic acid-2-ethylhexyl in molten salt hydrate

Examples

Experimental program
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Effect test

Embodiment 1

[0043] (1) 1000 mL of thioglycolic acid acidified solution was added to the distillation flask in stages, dehydrated and concentrated by vacuum distillation, and NaCl solid was centrifuged to obtain 200 g of distilled concentrated solution; the concentration of thioglycolic acid was 49.0 wt.%.

[0044] (2) Slowly add CaCl to the distilled concentrate 2 100g, the NaCl of solid will be continuously separated out, after the NaCl solid separated out, merge with the NaCl solid of the centrifugation of step (1) gained to form solid salt; Then adopt the water washing solid salt that step (1) steams 2 times, The washed water is returned to step (1), and the washed solid salt is dried and used as a by-product.

[0045] CaCl added to distilled concentrate 2 The molten salt hydrate is formed with the water in the distilled concentrate to obtain a distilled concentrate containing the molten salt hydrate.

[0046] (3) To the distilled concentrated solution containing molten salt hydrate...

Embodiment 2

[0052] (1) 800 mL of thioglycolic acid acidified solution was added to the distillation flask in stages, decompressed and dehydrated and concentrated, and the NaCl solid was centrifuged to obtain 150 g of distilled concentrated solution; the concentration of thioglycolic acid was 55 wt.%.

[0053] (2) the distilled concentrated solution of step (1) is slowly added in the lower layer aqueous phase concentrated solution of embodiment 1, the NaCl of solid will be continuously separated out, after the NaCl solid separated out, with the centrifugal separation of step (1) gained The NaCl solids are combined to form a solid salt; then the solid salt is washed twice with the water distilled from the step (1), the washed water is returned to the step (1), and the washed solid salt is dried and used as a by-product.

[0054] At the same time, add a small amount of CaCl 2 , such that CaCl 2 The concentration is 60wt.%, CaCl 2 The concentration is calculated based on the quality of the ...

Embodiment 3

[0061] (1) 800 mL of thioglycolic acid acidified solution was added to the distillation flask in stages, decompressed and dehydrated and concentrated, and the NaCl solid was centrifuged to obtain 150 g of distilled concentrated solution; the concentration of thioglycolic acid was 60 wt.%.

[0062] (2) the distilled concentrated solution of step (1) is slowly added in the lower layer aqueous phase concentrated solution of embodiment 2, the NaCl of solid will be continuously separated out, after the NaCl solid separated out, with the centrifugal separation of step (1) gained The NaCl solids are combined to form a solid salt; then the solid salt is washed twice with the water distilled from the step (1), the washed water is returned to the step (1), and the washed solid salt is dried and used as a by-product. At the same time, add a small amount of CaCl 2 , such that CaCl 2 The concentration is 60wt.%, CaCl 2 The concentration is calculated based on the quality of the distilled...

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Abstract

The invention relates to a preparation method of mercaptoacetic acid-2-ethylhexyl ester in molten salt hydrate, and belongs to the technical field of organic synthesis. Including the distillation and concentration step of thioglycolic acid acidified solution; adding CaCl 2 The steps of obtaining a distillation concentrate containing molten salt hydrate; the esterification reaction step of using the molten salt hydrate as the reaction medium; the steps of sedimentation and layering to obtain thioglycolic acid-2-ethylhexyl ester. The invention integrates the separation of thioglycolic acid, the treatment of tail-extraction wastewater, and the esterification reaction, greatly simplifies the production process, can effectively separate water and solid salt, and the content of organic matter in water and solid salt is low, and the separated water It can be reused, and the solid salt can also be used as a by-product. The invention greatly reduces the side reaction in the production process of thioglycolic acid-2-ethylhexyl, improves the yield and reduces the production cost.

Description

technical field [0001] The invention relates to a preparation method of mercaptoacetic acid-2-ethylhexyl ester in molten salt hydrate, and belongs to the technical field of organic synthesis. Background technique [0002] Thioglycolic acid-2-ethylhexyl is one of the main raw materials for the preparation of ester tin heat stabilizers. With the wide use of ester tin heat stabilizers, the demand for thioglycolic acid-2-ethylhexyl continues to grow , the export volume is also rising steadily. Thioglycolic acid-2-ethylhexyl is usually prepared by esterification of thioglycolic acid with 2-ethylhexanol. [0003] At present, the main synthesis methods of thioglycolic acid include thiourea method, sodium hydrosulfide method, sodium thiosulfate method, sodium polysulfide method, sodium trithiocarbonate method, alkyl sulfonate method, etc. The production of thioglycolic acid by the sodium hydrosulfide method has the advantages of simple process, readily available raw materials, and...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C319/12C07C323/52
CPCC07C319/12C07C323/52
Inventor 王景华于龙张广俊崔洪友
Owner 山东沾化金嘉利化工科技有限公司
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